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Publication numberUS3970919 A
Publication typeGrant
Application numberUS 05/588,735
Publication dateJul 20, 1976
Filing dateJun 19, 1975
Priority dateJun 19, 1975
Publication number05588735, 588735, US 3970919 A, US 3970919A, US-A-3970919, US3970919 A, US3970919A
InventorsDaryl T. Butcher
Original AssigneeThe United States Of America As Represented By The Secretary Of The Air Force
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Regulating digital power supply
US 3970919 A
A regulating digital power supply in which an error detector compares a reference signal voltage with an unknown loop signal voltage and upon being strobed the error detector outputs a signal depending upon the relative magnitude of the two input signals. This output signal controls the direction of count of an up/down counter that counts clock pulses. At appropriate intervals as controlled by the clock, the contents of the up/down counter are transferred to a down counter upon a command signal which also sets a flip-flop. When the down counter reaches zero and overflows it emits a signal that resets the flip-flop, the output thereof being a pulsewidth modulated regulated power supply. The flip-flop also controls a switch to a power source that is rectified and filtered and then fed back to the error detector comparator, thereby completing the loop.
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What is claimed is:
1. A regulated digital power supply system comprising:
a. a clock;
b. a frequency divider fed by the clock;
c. means for comparing a reference signal with an unknown signal upon application of a strobe pulse from the frequency divider;
c. a first means for counting pulses, the first counting means counting the pulses from the frequency divider and being fed by a signal from the comparing means for controlling selectively the direction of the count;
d. a second means for counting pulses, the second counting means counting pulses from the clock in the down direction and being fed by the contents of the first counting means upon a transfer command signal through the clock;
e. a flip-flop being set by the transfer command signal and reset by the second counting means upon reaching an overflow, the output of the flip-flop being the regulated power supply;
f. a source of power; and
g. a power switch interposed between the source of power and the comparing means and activated by the flip-flop for controlling the magnitude of the unknown signal.
2. A regulated digital power supply system according to claim 1 wherein the comparing means comprises first and second transistors having grounded sources and the gate of each transistor being connected to the drain of the other transistor and with the reference signal, the unknown signal, and the strobe pulse being resistively applied to the collectors.
3. A regulated digital power supply system according to claim 2 which further comprises:
a. a rectifier; and
b. a filter fed by the rectifier, with the rectifier and the filter being interposed between the power switch and the comparing means.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.


This invention relates to regulated power supplies, and more particularly to a digital power supply regulator using pulse counts and a feedback servo loop.

Analog MOS circuitry is extremely sensitive to radiation and there are undesirable results when not placed in a suitable radiation-free environment. The present invention is a regulated power supply but instead of using conventional analog techniques that have high sensitivities to radiation, a digital system is disclosed which is relatively insensitive to radiation.


A pair of transistors regenerates with one or the other conducting with the opposite being in the off state. Their states depend on the relative magnitude of an unknown loop voltage and a reference voltage, the regenerating output occurring each time a strobe pulse is applied. At each comparison or strobe pulse, an up/down counter is incremented (unknown less than reference) or decremented (reference less than unknown) and the contents of this register is transferred to a down counter and a flip-flop is set. A clock pulse with a repetition rate N times the strobe pulse rate is used to decrement the down counter until the zero count is past and an overflow occurs which resets the flip-flop. The width of the flip-flop output pulse is therefore controlled by the number contained in the up-down counter which is in turn controlled by the relative magnitude of the unknown and reference voltage. If the flip-flop pulsewidth is used to control or modulate a power inverter whose output is the unknown input to the comparator, a feedback loop is established. This loop causes the up/down counter number to converge on a value where the unknown and reference are equal within quantization errors. A servo loop for a digital power supply (or other application) can then be realized.

It is therefore an object of this invention to provide a novel and improved regulator digital power supply with greater efficiency than those used in the past.

It is another object to provide a regulated power supply having a pulsewidth modulated output signal.

It is still another object to provide a regulator power supply that has minimum sensitivity to radiation, unlike analog MOS circuitry that is extremely sensitive to radiation.

These and other objects, features and advantages of the invention will become more apparent from the following description taken in conjunction with the illustrative embodiment in the accompanying drawings, wherein:


FIG. 1 is a block diagram showing an embodiment of the regulated digital power supply which is the subject of the present invention; and

FIG. 2 is a circuit diagram of the comparator used as an error detector in the embodiment of FIG. 1.


Referring to FIG. 1, it can be seen that a reference voltage from reference source 11 is compared with another voltage which is the unknown voltage. The reference voltage can be any convenient DC voltage and the unknown voltage is obtained from the circuit loop. The reference voltage from source 11 and the unknown loop voltage are fed to comparator 13. This circuit is an error detector which produces a particular output voltage depending upon which of the two voltages, the reference voltage or the loop voltage, has the greater magnitude. The output voltage showing the direction of error is only produced if comparator 13 is strobed by a pulse originating from a clock source.

In FIG. 2, there is shown details of comparator 13. A pair of transistors 15 and 17 are interconnected with the gate of transistor 15 being connected to the drain of transistor 17 and the base of transistor 17 being connected to the collector of transistor 15. The sources of both transistors 15 and 17 are connected to ground. The reference voltage from source 11 is connected through resistor 19 to the collectors of transistors 15 and 17 and the unknown loop voltage is also connected to the drains of transistors 15 and 17 but through resistor 21. The strobe pulse is applied to the collectors through parallel resistors 23 and 25. When the circuit is strobed and depending on the relative magnitude of the loop voltage and the reference voltage, transistor 15 will be cut off and transistor 17 will conduct, or, transistor 17 will be cut off and transistor 15 will conduct. These conditions will result in a power output voltage taken at the collector of transistor 17.

Pulses are produced from clock 27 which has the frequency fo and are fed to frequency divider 29 which can be a counter. This circuit divides by N and output pulses are generated having a frequency of fo/N which both pulses up/down counter 31 and strobes comparator 31. At each comparison of the reference voltage and the loop voltage which occurs at each strobe pulse from divider 29, an output signal is fed to counter control 33 which causes counter 31 to count selectively either up or down. If the loop voltage is less than the reference voltage, then the counter 31 will be incremented; if the reference voltage is less than the loop voltage, counter 31 will be decremented. Each output stage of the up/down counter 31 is connected to corresponding stages of down counter 35. The contents of up/down counter 31 is transferred to down counter 35 upon a transfer pulse from clock 27 through timing gates 37. These timing gates are controlled through clock 27 and can be a delay. At the same time that the contents of up/down counter 31 are transferred to down counter 35, flip-flop 39 is set. A pulse from clock 27, having a frequency fo or N times the frequency of the strobe pulse, decrements down counter 35 until an overflow occurs, indicating that down counter 35 has passed the zero count. A signal from down counter 35, as a result of the overflow, resets flip-flop 39. The width of the output of flip-flop 39 is therefore controlled by the number contained in up/down counter 31 which in turn is controlled by the relative magnitude of the reference voltage and the loop voltage. Flip-flop 39 modulates the signal from power source 41 by activating power switch 43 which controls the signal to rectifier 45 followed by filter 47. The output of filter 47 is then fed back to comparator 13 completing the loop. Thus a feedback loop is established which causes up/down counter 31 to converge on a value where the loop voltage and the reference voltage are equal within the quantization errors. The digital output is taken from flip-flop 39 which is a signal modulated by pulsewidth.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3691452 *May 3, 1971Sep 12, 1972Western Union Telegraph CoControl of ac power by a logic comparator
US3735241 *Dec 28, 1971May 22, 1973Engineering Inc TPoly-phase digital controller
US3818321 *Apr 9, 1973Jun 18, 1974Wilorco IncVoltage regulator
Non-Patent Citations
1 *"A-D Transistor Switching Regulator Controller" by Calvo et al. IBM Tech. Disc. Bull. vol. 17, No. 9 Feb. 1975 pp. 2666, 2667.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4260947 *Oct 11, 1977Apr 7, 1981Massey David TPhase control circuit for regulating power
US4287437 *Nov 29, 1979Sep 1, 1981International Business Machines Corp.Method and circuitry for equalizing the differing delays of semiconductor chips
US4346343 *May 16, 1980Aug 24, 1982International Business Machines CorporationPower control means for eliminating circuit to circuit delay differences and providing a desired circuit delay
US4356542 *Mar 11, 1981Oct 26, 1982Ncr CorporationDigital controller
US4387399 *Jun 30, 1981Jun 7, 1983Itt Industries, Inc.Power supply switching-regulator particularly for television receivers
US4639660 *Mar 19, 1985Jan 27, 1987Pioneer Electronic CorporationSwitching circuit for a power supply in a signal processing apparatus
US4725769 *Apr 9, 1987Feb 16, 1988Sgs Microelettronica S.P.A.Current limited for constant current for switching driving devices
US5426387 *Feb 11, 1993Jun 20, 1995Societeanonyme Dite: Labratoires D'hygiene Et De DietetiqueDevice for generating an electrical voltage of predetermined waveform, iontophoresis apparatus for transdermally administering medicinal products and electrical stimulation apparatus, which apparatuses are equipped with such a device
US5432693 *Apr 1, 1993Jul 11, 1995Ford Motor CompanyDigital pulse width modulator circuit with proportional dither
US5499967 *Jan 13, 1994Mar 19, 1996Societe Anonyme Dite: Laboratoires D'hygiene Societe Anonyme Dite: Et De Dietetique (L.H.D.)Transdermal drug delivery device with waveshape generator
US5982157 *Feb 13, 1998Nov 9, 1999Asulab S.A.Chopper-amplifier for the voltage of a photovoltaic power source, in particular for a timepiece
US6204651 *Apr 18, 2000Mar 20, 2001Sigmatel, Inc.Method and apparatus for regulating an output voltage of a switch mode converter
US6294905May 2, 2000Sep 25, 2001Stmicroelectronics GmbhMethod and circuit for controlling current in an inductive load
US6351162May 2, 2000Feb 26, 2002Stmicroelectronics GmbhCircuit arrangement for controlling an inductive load
US6703810Oct 24, 2002Mar 9, 2004Dialog Semiconductor GmbhDigital controlled charge current regulator
US6791305 *Feb 24, 2003Sep 14, 2004Tdk CorporationSwitching power supply control circuit and switching power supply using same
DE3418939A1 *May 22, 1984Nov 28, 1985Telefunken Electronic GmbhPower controller for electrical loads
DE3418940A1 *May 22, 1984Nov 28, 1985Telefunken Electronic GmbhPower controller for electrical loads
DE3638957A1 *Nov 14, 1986May 19, 1988Bosch Gmbh RobertDC voltage control circuit (regulating circuit)
DE19920306A1 *May 3, 1999Nov 16, 2000St Microelectronics GmbhSchaltungsvorrichtung zum Regeln einer induktiven Last
DE19920306B4 *May 3, 1999Feb 28, 2008Stmicroelectronics GmbhSchaltungsvorrichtung zum Regeln des Stroms durch eine induktive Last
DE19920307A1 *May 3, 1999Nov 16, 2000St Microelectronics GmbhElektrische Schaltung zum Steuern einer Last
EP0012839A1 *Nov 19, 1979Jul 9, 1980International Business Machines CorporationMethod and device for adjusting the different time delays of semiconductor chips by changing the working voltage
EP0214781A1 *Aug 15, 1986Mar 18, 1987General Motors CorporationGenerator voltage regulating circuit
EP0520480A2 *Jun 26, 1992Dec 30, 1992Kabushiki Kaisha TECHigh-voltage power source control device
EP0558409A1 *Feb 24, 1993Sep 1, 1993LABORATOIRES D'HYGIENE ET DE DIETETIQUE L.H.D. Société Anonyme dite:Device for generating an electric voltage having a predetermined waveform and iontophoretic transermal drug delivery apparatus, equipped with such a device
EP0859454A1 *Feb 17, 1997Aug 19, 1998Asulab S.A.Switch mode booster of a photovoltaic source voltage, especially for a timepiece
EP1050965A2 *May 2, 2000Nov 8, 2000STMicroelectronics GmbHElectrical circuit for driving a load
EP1387479A1 *Aug 2, 2002Feb 4, 2004Dialog Semiconductor GmbHDigital controlled charge current regulator
WO1982003141A1 *Mar 8, 1982Sep 16, 1982Ncr CoRegulated power supply
U.S. Classification323/283
International ClassificationG05F1/10, H02M3/157, G05B11/28
Cooperative ClassificationH02M3/157, G05B11/28, G05F1/10
European ClassificationH02M3/157, G05F1/10, G05B11/28